Optical pattern projection is used in a variety of applications, such as optical three-dimensional (3D) mapping, area illumination, and LCD backlighting. In some applications, diffractive optical elements (DOEs) are used in creating a desired projection pattern.
Various methods are known in the art for designing DOEs. In some of these methods, the DOE is designed as a phase mask, which corresponds, in effect, to a Fourier transform of the far-field amplitude pattern that the DOE is to project. A method for computing such phase masks is described, for example, by Gerchberg and Saxton in “A Practical Algorithm for the Determination of the Phase from Image and Diffraction Plane Pictures,” Optik 35 (1972), pages 237-246, which is incorporated herein by reference. Fienup reviews computational approaches that may be used in designing phase-mask DOEs in “Phase Retrieval Algorithms: A Comparison,” Applied Optics 21, 2758-2769 (1982), which is also incorporated herein by reference.
Sazbon et al. describe how the Gerchberg-Saxton algorithm may be used in designing a DOE for use in range estimation, in “Qualitative Real-Time Range Extraction for Preplanned Scene Partitioning Using Laser Beam Coding,” Pattern Recognition Letters 26 (2005), pages 1772-1781, which is also incorporated herein by reference.